FIG. 1 is a cross-sectional view of a prior art light emitting diode (LED) package 10. Package 10 contains an LED chip 12 having cathode and anode contacts coupled, via metal interconnects 18, to metal pads 14 on a ceramic substrate 16. Metal vias 20 extend through substrate 16 and contact backside metal pads 22. The LED chip is encapsulated by epoxy 23. Package 10 is typically solder-mounted onto a printed circuit board or incorporated into another package. Such other package typically includes a lens, reflective walls, a base, and leads. The various metal interconnects in combination with the ceramic substrate 16 conduct heat from the LED chip 12 to the printed circuit board, which may include an additional heat sink.
LEDs are well known and are formed from semiconductor materials on a substrate. The LED chip 12 substrate material may be a semiconductor, a conductor, or an insulator.
LEDs can be damaged by high voltages from ESD. It is common to provide ESD protection for an LED, such as providing a separate ESD protection circuit in the LED package or on the printed circuit board. Providing a separate ESD protection circuit in the LED package may increase the size of the package and/or reduce the light-emitting area of the chip 12. Forming the ESD protection circuitry on the PC board or in the package also adds complexity in the manufacture of the PC board or package and thus adds cost to the circuit.
What is desirable is a technique for providing ESD protection without the need for forming ESD protection circuitry on the LED chip or as a separate element on the PC board or in the package.